Section 11 commutativity: product estimates #
Basic product-style lemmas on projective submeasurement outcomes, the expansion of the two
scalar-stability defects, and the commutator-expansion terms reused throughout the Section 11
commutativity argument: the counterpart of
MIPRE/Background/LIDT/MIPStarRE/LDT/Commutativity/Scaffold/Products.lean in the port of
planning/c6b-plan.md (milestone M7, section "Port conventions").
The expansion terms are expectations strategy.state.ev (strategy.state.L …) on the symmetric
model of the strategy; the vendored leftTensor (ι₂ := ι) and rightTensor (ι₁ := ι) are
strategy.state.L and strategy.state.R, and ᴴ is star. postprocess_proj_outcome is
generic over any C*-algebra with its order.
The vendored proofs of the two stability expansions restate the Kronecker products in every
step and prove self-adjointness through Matrix.PosSemidef; here both are one application of
stabilityDefect_ev_eq (below), whose proof uses the keystone's opTensor algebra and the
self-adjointness of nonnegative elements.
New here #
stabilityDefect_ev_eq, the per-outcome identity
ev((L(X T) R(√G) − L X R(√G))^* (L(X T) R(√G) − L X R(√G))) = ev(L((1 − T) X^* X (1 − T)) R G)
for self-adjoint T and 0 ≤ G, which the vendored file proves inline twice.
Not ported #
Every declaration of the vendored file has a counterpart here.
References #
In LionSR/MIPStarRE at commit 507e8122, not in this repository:
references/ldt-paper/commutativity-G.texblueprint/src/chapter/ch08_commutativity.tex
Postprocessing a projective submeasurement preserves outcome projectivity.
Evaluating a projective polynomial family at a point preserves outcome projectivity.
The positive square root of a submeasurement outcome squares back to that outcome.
The defect of a trailing self-adjoint factor T, weighted on the second factor by √G:
ev((L(X T) R(√G) − L X R(√G))^* (…)) = ev(L((1 − T) X^* X (1 − T)) R G).
Fixed-question expansion of the first scalar-stability qSDDOp term.
This is the pointwise algebra behind the paper's G^y insertion/removal step:
the left-register defect is sandwiched by 1 - G^y, while the right-register
weight is the projective outcome G^y_h.
Fixed-question expansion of the second scalar-stability qSDDOp term: the
left-register defect is sandwiched by 1 - G^x, while the right-register weight is the
projective outcome G^x_g.
The BAB term in the evaluated-slice commutator expansion.
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The ABA term in the evaluated-slice commutator expansion.
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The BABA term in the evaluated-slice commutator expansion.
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The ABAB term in the evaluated-slice commutator expansion.
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The first evaluated-slice factor viewed as a projective family.
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- MIPRE.LIDT.Co.Commutativity.evaluatedSliceFirstProj params family q = { toSubMeas := MIPRE.LIDT.Co.Commutativity.evaluatedSliceFirstFactor params family q, proj := ⋯ }
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The second evaluated-slice factor viewed as a projective family.
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- MIPRE.LIDT.Co.Commutativity.evaluatedSliceSecondProj params family q = { toSubMeas := MIPRE.LIDT.Co.Commutativity.evaluatedSliceSecondFactor params family q, proj := ⋯ }
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The first full-slice factor viewed as a projective family.
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- MIPRE.LIDT.Co.Commutativity.fullSliceFirstProj params family q = family.meas q.1
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The second full-slice factor viewed as a projective family.
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- MIPRE.LIDT.Co.Commutativity.fullSliceSecondProj params family q = family.meas q.2
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The BAB term in the full-slice commutator expansion.
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The ABA term in the full-slice commutator expansion.
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The BABA term in the full-slice commutator expansion.
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The ABAB term in the full-slice commutator expansion.
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